Best I Can Get On A $400 Budget? Help

Hello rmpsrpms,
You wrote earlier.......
""That is true, the minimum extension of the bellows may be too long to capture larger coins with 50mm. 75mm or 80mm may work better...Ray

Edited to add:

I wrote the following to another forum member to explain the above, and thought I'd post it here:

The reason the shorter lenses are higher magnification than longer lenses is that the minimum extension of the bellows is a fixed length. The formula for magnification is:
M = (TE-FL)/FL
Where TE = Total Extension and includes the 44mm of sensor to lens mount distance. A typical bellows has 45mm of minimum extension. You also need some adapters, which add perhaps 11mm. So the shortest you can make the TE is around 100mm.
So for a 100mm lens, you can achieve M=0, or infinity focus.
For a 75mm lens, you can achieve minimum M=0.33, which will comfortably allow a Dollar to be framed on APS-C
For a 50mm lens, you can achieve a minimum M=1, which will not even allow a Cent to be framed on APS-C
For a 35mm lens, you can achieve a minimum M=1.85

Thank you Ray for this information. My camera body is the Canon 40D so it is good to know the formula. I am glad you also mentioned the extra 44mm from the sensor to the lens. It is certainly good for my mind to have this new use of my old photo equipment.
I am gaining useful knowledge from being a new member of the family. Thank you once again Ray for your attention to this newbie.
Regards.

rocky, thanks for the tips and information. I have Ray's setup, but was looking to upgrade my 75mm lens. I was wondering if an 80mm would work better with my setup. I am having to raise the microscope stand about 4 inches to get a full PCGS slab shot. What do you think Ray?

Yes, Ray, I should of known that. Thanks for the clarification.

Ham...please remind me...are you currently using bellows, or extensions + helicoid? If bellows, then the 60mm won't work because the minimum extension is too long. If you're using a helicoid, then it might work if you have the 17-31mm helicoid. The formula is:

M = (TE-FL)/FL

Re-arranging...TE = FL(M+1)

For a full Slab view, you need a vertical field of view of perhaps 65mm (OGH). The sensor on a Canon APS-C camera is approx 15mm tall, so the magnification is 15/65=0.23

For Canon, the TE is 44mm + the added extension. So the added extension is FL(M+1)-44

If FL=60, and M=0.23, then you need to add 60(1.23)-44 = 30mm of extension. This fits nicely with the 17-31 helicoid at nearly full extension.

But note that the 30mm extension explains why the bellows won't work. The minimum extension of most bellows is in the range of 45mm.

When talking about bellows, you must include the adapters. For T-Mount bellows like the Vivitar, it's usually the adapters that cause the most problems. T-Mount adapters are typically pretty long. For example, T-EOS adapters are around 11mm. The T-M39 or T-M42 adapters are around 3-4mm. This brings you up to the 45mm I was talking about above.

I'm looking for a good Rodenstock APO Rodagon D 75mm f/4 Enlarging Lens. I have found a couple on ebay for $375 (new) and $345 (used). There is another that looks to have a large scratch. Current bid $66. Does anyone in this forum know of a better deal? I would appreciate comments about the 3. Links for the above mentioned.
http://www.ebay.com/itm/33141070452...RK:MEBIDX:IT
http://www.ebay.com/itm/12179764943...RK:MEBIDX:IT
http://www.ebay.com/itm/27202501278...RK:MEBIDX:IT

I would like to be able to take images of a PCGS slab with out having to elevate my microscope stand 4 inches. I do exclusively dollars. Do you have a copy stand recommendation?